Infrastructure at your Service
By Franck Pachot . Those parameters, SQLNET.EXPIRE_TIME in sqlnet.ora and ENABLE=BROKEN in a connection description exist for a long time but may have changed in behavior. They are both related to detecting dead TCP connections with keep-alive probes. The former from the server, and the latter from the client.
By Franck Pachot . Microsoft SQL Server has implemented MVCC in 2005, which has been proven to be the best approach for transaction isolation (the I in ACID) in OLTP. But are you sure that writers do not block readers with READ_COMMITTED_SNAPSHOT? I’ll show here that some reads are still blocked by locked rows, contrary to the precursors of MVCC like PostgreSQL and Oracle.
By Franck Pachot The Oracle Cloud is not only for Oracle Database. You can create a VM running Oracle Linux with full root access to it, even in the free tier: a free VM that will be always up, never expires, with full ssh connectivity to a sudoer user, where you are able to tunnel any port. Of course, there are some limits that I’ve detailed in a previous post. But that is sufficient to…
By Franck Pachot . I love databases and, rather than trying to compare and rank them, I like to understand their difference. Sometimes, you make a mistake and encounter an error. Let’s take the following example: create table DEMO (n int); begin transaction; insert into DEMO values (0); select n “after insert” from DEMO; update DEMO set n=1/n; select n “after error” from DEMO; commit; select n “after commit” from DEMO; The “begin transaction” is…
By Franck Pachot . COMMIT is the SQL statement that ends a transaction, with two goals: persistence (changes are durable) and sharing (changes are visible to others). That’s a weird title and introduction for the 499th blog post I write on the dbi-services blog. 499 posts in nearly 5 years- roughly two blog posts per week. This activity was mainly motivated by the will to persist and share what I learn every day.
By Franck Pachot . I know that lot of people are against the ANSI join syntax in Oracle. And this goes beyond the limits when talking about NATURAL JOIN. But I like them and use them quite often. Why is Natural Join bad? Natural join is bad because it relies on column names, and, at the time of writing the query, you don’t know which columns will be added or removed later. Here is an…
By Franck Pachot . This is research only and totally unsupported. When building docker images to run Oracle Database in a container, we try to get the smallest image possible. One way is to remove some subdirectories that we know will not be used. For example, the patch history is not used anymore once we have the required version. The dbca templates can be removed as soon as we have created the database… In this…
By Franck Pachot . In a previous post I described the setup of MiniShift on my laptop in order to run OpenShift for test purpose. I even pulled the Oracle Database image from the Docker Store. But the goal is to import it into OpenShift to deploy it from the Image Stream.
By Franck Pachot . Here is a quick post you may google into if you got the following error when running postupgrade_fixups.sql after an upgrade: ERROR – Cannot open the preupgrade_messages.properties file from the directory object preupgrade_dir DECLARE * ERROR at line 1: ORA-29283: invalid file operation ORA-06512: at “SYS.DBMS_PREUP”, line 3300 ORA-06512: at “SYS.UTL_FILE”, line 536 ORA-29283: invalid file operation ORA-06512: at “SYS.UTL_FILE”, line 41 ORA-06512: at “SYS.UTL_FILE”, line 478 ORA-06512: at “SYS.DBMS_PREUP”, line…
By Franck Pachot . You find two different ‘runInstaller’ under an Oracle Home. The old one, the Oracle Universal Installer, in $ORACLE_HOME/oui/bin. And the new one, in $ORACLE_HOME directly. They have the same name but are completely different. The old one was used to install an Oracle Home from the installation media. But in 18c you don’t use it. It has been used by Oracle to build the Oracle Home image. Then you download and…
